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| /* | |
| * Copyright (c) 2016-2020 Martin Donath <martin.donath@squidfunk.com> | |
| * | |
| * Permission is hereby granted, free of charge, to any person obtaining a copy | |
| * of this software and associated documentation files (the "Software"), to | |
| * deal in the Software without restriction, including without limitation the | |
| * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or | |
| * sell copies of the Software, and to permit persons to whom the Software is | |
| * furnished to do so, subject to the following conditions: | |
| * | |
| * The above copyright notice and this permission notice shall be included in | |
| * all copies or substantial portions of the Software. | |
| * | |
| * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR | |
| * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, | |
| * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL THE | |
| * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER | |
| * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING | |
| * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS | |
| * IN THE SOFTWARE. | |
| */ | |
| import { Observable, fromEvent, merge } from "rxjs" | |
| import { map, startWith } from "rxjs/operators" | |
| /* ---------------------------------------------------------------------------- | |
| * Types | |
| * ------------------------------------------------------------------------- */ | |
| /** | |
| * Element offset | |
| */ | |
| export interface ElementOffset { | |
| x: number /* Horizontal offset */ | |
| y: number /* Vertical offset */ | |
| } | |
| /* ---------------------------------------------------------------------------- | |
| * Functions | |
| * ------------------------------------------------------------------------- */ | |
| /** | |
| * Retrieve element offset | |
| * | |
| * @param el - Element | |
| * | |
| * @return Element offset | |
| */ | |
| export function getElementOffset(el: HTMLElement): ElementOffset { | |
| return { | |
| x: el.scrollLeft, | |
| y: el.scrollTop | |
| } | |
| } | |
| /* ------------------------------------------------------------------------- */ | |
| /** | |
| * Watch element offset | |
| * | |
| * @param el - Element | |
| * | |
| * @return Element offset observable | |
| */ | |
| export function watchElementOffset( | |
| el: HTMLElement | |
| ): Observable<ElementOffset> { | |
| return merge( | |
| fromEvent(el, "scroll"), | |
| fromEvent(window, "resize") | |
| ) | |
| .pipe( | |
| map(() => getElementOffset(el)), | |
| startWith(getElementOffset(el)) | |
| ) | |
| } |